In general, an LCD apparatus displays image using electro-optics properties of a liquid crystal. To display a high-quality image with the LCD apparatus, technologies of utilizing material properties of the liquid crystal, controlling the liquid crystal and improving optical properties of a light are required.
Even though the liquid crystal can be precisely controlled, the quality of the image depends on the optical properties of the light passing through the liquid crystal because the liquid crystal does not generate a light but only controls the transmissivity of the light incident from an external.
Thus, technologies for improving the optical properties of the light are rapidly developed with the technologies for controlling the liquid crystal.
The technologies for improving the optical properties of the light which transmits through the liquid crystal are classified into a technology for improving properties of a light source and a technology for improving the properties of the light from the light source.
In general, it is required that a surface light source such as sunlight is used as the light source of the LCD apparatus. However, since it is difficult to apply the surface light source to the LCD apparatus, a CCFL (Cold Cathode Fluorescent Lamp) having a line light source is widely used as the light source of the LCD apparatus.
The CCFL includes a lamp tube having a fluorescent material formed on an inner surface thereof and a discharge gas injected into the lamp tube and a pair of electrodes. The electrodes are facing to each other and are disposed in the lamp tube.
When applying discharge voltage to the electrodes, electrons are emitted from a first electrode of the electrodes toward a second electrode facing the first electrode. The electrons collide with the discharge gas to dissociate the discharge gas, so that a plasma state is formed in the lamp tube.
An invisible ray generated by colliding the electrons with the discharge gas is changed into a visible ray while passing through the fluorescent material.
When a plurality of CCFLs are connected to a power supply unit in parallel and the plurality of CCFLs are simultaneously turned on, those CCFLs are turned on to have a non-uniform brightness. In addition, the CCFL has a high power consumption.